Late in the evening of 4th May a staff member from Richmond Primary School reported to my home what they thought to be a dead or badly injured eagle near the side of Pittwater Rd they saw while walking their dog.
The bird was indeed dead and had classic signs of a massive electrocution (see pictures). I immediately reported the dead eagle with photos, through Tasnetwork’s website saying exactly where it was found and on 6th May received an acknowledgment of my report and phone message from their environment section.
The eagle was stone cold so had been dead for many hours and the mud on its beak but lack of spattered mud and sand suggested it had fallen after the last heavy rain on Sunday 1st. Lots of people walk past there so it can’t have been down long – probably between late on the 3rd or early on the 4th. A resident along the power lines beyond where the eagle was found tells me they had a 3 hour blackout on the 3rd so I guess that’s when it was killed.
It was an adult male wedge-tailed eagle Aquila audax (a federally and state endangered subspecies). It was almost certainly a member of one of 3 pairs within range of Richmond, most probably the most local pair that many Richmonders appreciate as they hunt rabbits and hares along Butchers Hill and pass over the town stirring up other raptors, chooks, ravens, galahs and cockatoos (and bird watchers).
Aside from burns the bird was in prime condition. There appeared a massive short between the knee and adjacent wing base with a very strong smell of burned feathers. Superficial (but experienced) examination showed no other injury. As with most such cases involving the body proper the bird probably died instantly.
The bird was under a typical configuration of 3 parallel wires in the same plane distributing power to several houses. It was well away from a pole and very far from the adjacent high tension power lines. What seems to happen in these cases is the bird hits the first (outside) wire and being heavy (more than 4 kg) carries into the second earthing . Birds with less momentum hitting the first wire usually do not carry enough to arc on the second. I have seen both things happen.
I have been told that such shorts register as a fault and that a search is carried out for the cause. That certainly happens at a transformer near me that regularly kills birds (with a very loud bang) but it seems the ‘system’ may not be effective all the time. This recent outage was apparently fixed but the bird not found (if the bird was found by power authorities they would retrieve it). As you can see the bird couldn’t be more obvious and indeed 4 different people have told me they saw it that day so it would seem no proper search was carried out.
A conversation today with a representative of Tasnetworks environment section reveals a search was carried out but essentially only of the wires per se looking for any obvious problem. The eagle lying under the wires, plain as day, was not seen so the outage goes down as “cause unknown’, the most common category. One cant help but wonder how many are indeed caused by birds but not recorded as such because of priorities in searches.
Promptness in searching is important too in that electrocuted birds can be scavenged or otherwise removed and therefore not found by late searchers.
It’s not an academic issue since I have long argued with power authorities that there are probably many more birds hitting wires and/or getting electrocuted than they acknowledge. I suspect many large birds found injured roadside presumed hit by vehicles, have actually hit wires – I once saw two fighting brown falcons Falco berigora tumbling earthwards pile into such wires, one being decapitated and falling dead, roadside and the other breaking a leg and a wing falling on the road.
It would seem that besides more collisions, there also may be more electrocutions than recorded. We really have to better match what actually happens with what’s recorded to allow realistic cost/benefit analyses for improving wiring configurations.
Editor’s note: this is an updated version of the article.
Nick Mooney is a wildlife ecologist who lives near Richmond, Tasmania.